Non-equilibrium models with partonic degrees of freedom can trace the dilepton emission from initial state dynamics consistently by following the collision history of the partons explicitly.
In the pHSD model, the initial state parton collisions are obtained from the event generator PYTHIA [1]}.
Leading partons can re-scatter and strings either hadronize according to the rules of PYTHIA or melt into partons if the energy density of the surrounding medium exceeds 0.5  G\(e\) V fm\(^3\) .
Partons are treated as dynamical quasi-particles with spectral functions depending on the medium properties.
Dileptons are mainly produced in bremsstrahlung-like \(qg\)  or \(\bar{q}g\)  quark-gluon scatterings or in \(q\bar{q}\)  annihilation processes.
For details see [2]}.
Since the partons are dressed in this approach, the respective dilepton spectrum from \(\bar{q}q\)  annihilation is cut off towards small invariant masses.
